Apparatus for magnetically separating materials



Oct. 3l, 1939. A'L QUENEAU 2,177,809

APPARATUS FOR MAGNETIALLY SEPARHTING `MATERIALS Filed May 5, 1937 3 Sheets-Sheet 1 m l i @Q Il e L] E i I I D l 1 O I i lq i i I I I." u is f 1 R w s lm L l I- "-3 l El N INVENTOR, UGUJ77%LEQNC=AAL%VEAU. ATTORNEYS Oct. 3l, 1939. A, L, 1 QUENEAU 2,177,809

APPARATUS FOR MAGNETICALLY SEPARATING MATERIALS Filed May 5, 1957 3 sheets-sheet 3 v INVENTOR.

Aucasr//vlfa/vw/y QuE/V540. 22a ATTORNEYS Nm wm M A A A mi Patented Oct. 31, 129379 'PATENT omer.

APPARATUS FOB MAGNETICALLY SEPARATING MATERIALS Augustin Leon Jean Queneau, Bernardsville, N. J. Application May 45, 1.937, Serial No. 140,930

z claim.. (orcos-219) This invention relates to magnetic separator devices and more` particularly to devices adapted to economically segregate by magnetic means'v l5 jects and advantages will be apparent as the invention is more fully disclosed. v In accordance with the above objects I have devised an electromagnetic separator device of which the following description together with the 20 'accompanying' drawings is a full and complete disclosure. In the drawings, Fig.v 1 is a top plan view of the device of the present invention; Fig. 2 is a side view in section of the same; Fig. 3 is an enlarged view illustrating one feature of thek 25 same; Fig-4 is an enlarged view illustrating another feature of the same; Fig. 5'is an enlarged section illustrating still another feature of the same; Fig. 6 is a perspective view of one' im Referring to these drawings, the kdevice of the present invention consists ina novel type of elec- 35 tromagnet together with means to feed the material to be treated to the magnet and means to segregate the magnetically attracted particles f from thenon-magnetic particles. 'I'he electromagnet' of the present invention 4 consists essentially of a pole piece I (Fig. 6) rectangular in section, one end 2 of the polev piece .being arcuately recessed between opposite rectangular sides oredges, and being provided with v`"an arcuately shaped non-magnetic shield 24 formf ing with said recess a cylindrical bore passage- .way 3 the cylindrical axis of which lies substantially coincidentally with the axis of. the rounded surface of shield 2. Shield 2 is comprisedIoi j 'non-magnetic material such as a stainless aus- 50 tenitlc Fe.Cr.Ni alloy.. A cylindrical end piece l '4 (Fig.5) con'lprisedk of magnetic material is ro-` tatablysupportedwithin said recess 3, the pex ripheral cylindricalsuriace o! which end piece is provided with a pluralityv of spaced and isolated points orareas 5 comprised of material of relatively high magnetic iiux permeability as compared to the intermediate areas' 0 thereof, the said spaced and isolated points or areas i forming a substantially discontinuous path circumferentiially about the peripheral surface oi' thesaid end i5 p ece.

The rectangular size of pole l may be varied markedly without departure from the present invention as will be apparent from turther description. l0

Ihave i'ound that by disposing two of these poles horizontally with the rounded non-magnetic ends in space gap relation as indicated in Figs. 2 and 8. and by passing a magnetizing current across this space gap, I may feed material l5 i0 gravitationally onto the curvedI non-magnetic surface or eitheror both pole ends, and by rotating the cylindrical end pieces 4, I can eiiectively cause the magnetically attracted particles of the material lli to be progressively moved downwardly along the curved surface through the zone of maximum vflux density and thence through a decreasing magnetic field along the under side oi.' the curved surface to the point where the ux density can no longer retain the 25 particle adjacent the non-magnetic surface against the vertically downward gravitational pull. Thev non-magnetic particles of the material fall vertically oil' the lip of the curved surface and by the provision of adjustableI gatemeans Il I/.may accordingly obtain a relatively clean separation'between the magnetic' and nonmagnetic particles.

The essential problem involved is to economically provide a' magnetic field of. adequate 35 strength to magnetically attract and hold the desired particle to the non-magnetic surface against the gravitational pull and other interfering forcesincident to the gravitational passage v of the material through the magnetic field. 40

- This problem is essentially one ci magnet design and the most effective and eilicient design that Ihave found is that indicated in the draw- -l ings. The electromagnetic coil l2 is wound about the pole las close tothe rounded end as is pracyspaced poles I dispose rectangular yoke member I3 forming" a substantially closed magnetic path horizontally on either side of the space gap between the non-magnetic pole ends. Coils IZ-II' 55 ployed in accordance with the present invention,

as indicated in Figs. 2 and 8.

The feeding of material to be treated through the space gap and gravitationally along the curved non-magnetic surface of the pole end may be accomplished in a plurality of ways without departure from the present invention. In Figs. 2 and 8 I have shown one convenient way of doing this. The essential feature of the feeding means is to deposit the material upon the upper curved surface in a relatively thin layer, not over 2 or 3 particles deep, so that entrapment of non-magnetic particles by the magnetic particles is substantially avoided. In the arrangement shown, the material I0 is fed through spout I4 into chamber I5 provided with a deflection plate I6 which carries the material gravitationally to the opposite side walls of container I5 and to a slit opening I1 adapted to permit the material I0 to trickle therethrough upon inclined plate I8 forming a tangential continuation of the curved outer surface of shield 2 at y justing gate means II.

such an angle as will with respect to the particle size and specific gravity of material I0 promote a gravitational oW of the material I0 at a desired rate downwardly along the said 'non-magnetic curved surface of shield 2.

The magnetic field strength should be sufficient to retain the magnetic value desired to be separated adjacent the outer curved surface of shield 2. This field strength will vary with respect to the particular magnetic susceptibility of the magnetic values.l

Rotation of cylindrical end piece 4 in the direction of material flow may be at various rates depending upon the rate of flow of materia.1 I0, the relative amount of magnetic and non-magnetic particles therein, the magnetic susceptibility and field strength, for example. I have found that the rate of travel of the peripheral surface of the'pole end should closely approximate the rate of flow of the material I0 for best results on the majority of materials and over a relatively wide range of concentrations of magnetic and non-magnetic constituents.

In the ordinary practice of the present invention, the non-magnetic particles of material I0 will be collected in center compartment A and the magnetic particles collected in outer compartments B-B' (Fig. 2) or'in compartments A and B respectively (Fig. 8), the division being made possible and positive through operation of adjustable gate means II. In Fig. 4 I have illustrated a very convenient arrangement for ad- The gates II are mounted on rotatable shafts I9-I9 the ends of which y protrude through the end walls of container I5 maximum field strength will be located.

In the use and application of the present invention, it is' apparent that the economic treatment of some materials, such as low grade or low cost material, will require a single device to handle relatively large tonnages of materials during a unit time interval. This may be accomplished through lengthening the rectangular section of the pole piece, thereby producing a relatively long rectangular gap through which the material III may be passed, substantially as indicated in Fig. 1. As the length of cylindrical end section 4 is increased, however, lthe difculties of rotatively supporting the same within the bore passageway increases, and to avoid the use of relatively heavy axles and to reduce the energy required to rotate the end piece, I have designed the structure indicated in Fig. 5.

In Fig. 5 the cylindrical end section 4 is comprised substantially of a tubular length 4 of low metalloidsteel having a total length substantially less than the overall length of pole I but approximately that of curved end piece 2 (Fig. 6). The outer peripheral surface of tube Il is provided with a plurality of spaced grooves extending longitudinally the entire length of the tube. In each groove I dispose and s eat strips 5 comprised of material of relatively high flux permeability, such as cobalt steel, which strips 5 extend above the peripheral surface of tube 4 with the intervening spaces between the extending sides 4of strips 5 lled with material 25 of' low magnetic flux permeability, such as lead solder having a permeability substantially that of air. The combination of tube 4 with areas 5 and 25 I will hereinafter identify as a rotor 4.

I prefer to provide strips 5 with a longitudinal groove or recess 24 (as indicated in cross-section in Fig. 4) and as a specific embodiment of this structure strips 5 are comprised of cobaltsteel having a cross-sectional dimension of 1%; inch .by one inch and a length approximating the length of the tube 4. These strips are recessed edgewise into the surface of tube 4 about V2 inch and the space 25 between the strips is filled with lead solder to a level approximating that of the upper surface of the strips 5. The

upper surface of strip 5 is provided with a centrally located recess 24 aproximately 1/8 inch wide by 1/8 inch deep. This arrangement `provides a flux density ratio between the cobalt strip and the intervening solder of about 8:1; for example, With an exciting current of two amperes a flux density of about 13,000 gausses will be obtained on the cobalt strips while only about 1680 gausses will be obtained on the lead solder. This provides an ample flux differential between the strip 5 and intervening material 25 to obtain the desired movement of the magnetically attracted particles through the magnetic eld. The longitudinal groove or recess 24 in strip 5 accentuates the effect desired from this flux differential in some manner not at this moment apparent. It may be that by multiplying the number of sharp corners present on strip 5 by the provision of recess 24 this accentuated effect is obtained.

To the inside of this rotor I afx a driving Vable means such as a variable speed back drive electric motor through suitable gearing 33.

By the use of this rotor structure Imay economically extend the length of cylindrical end section 4 to thirty inches or more without proportionately increasing the diameter thereof, and

thereby markedly increasing the capacity per time l unit of the device of the present invention without seriously increasing the cost of the device. It is necessary, however, to increase the coil turns of coils |2--2' to provide for the increased magnetic currents thereby required. One skilled in the art may readily calculate the number of coil turns required to obtain a desired magnetic current when given any particular pole area from which to figure.

As an example of the practical utility of the present invention, I may treat a ferruginous sandstone ore consisting principally of hematite and silica found principally in the Alabamairon ore district as follows:

'The ore is crushed and ground carefully to .free the hematite from the silica. In this type ore the individual grains of silica are coated or cemented together by the hematite. It is exceedingly diicult to crush the ore in such a way as to avoid breaking the silica grains and to entirely free the surfaces of the silica grains from adhering crusts of hematite. 'I'he magnetic suscep tibilities of these two materials are not far apart: hematite=1.32 and silica=.37 (iron as a standard being taken at 100). Therefore it is apparent the successful application of any method of magnetic separation will depend primarily upon the efficiency of the grinding process and the extent the individual silica grains are freed from the surface coating of hematite. The most, effective mode of grinding that I have found to accomplish this,

is to first crush the ore to about 1/ inch size in an ordinary rock crusher, then to place the material in a rod mill and to grind slowly therein for a prolonged time interval. The thus ground material should then be screened through 20' mesh, the oversize particles returned to the rod mill and the material passing the screen subjected to magnetic separation in the device of the l present invention.

In treating the thus ground ore in the device of the present invention, I have found it preferable to recover the iron content of the ore in steps. The ore after grinding averages about 25.0% Fe (as FezOa) and the bulk of the relmainder is silica.

During the first passage lof the ore through the device I apply a relatively low iiux density in order to remove substantially all of the iron present as magnetite (Fe'sOi) the more magnetic ironoxide. to about I13,000 gauss and then to about 19,000 gauss, the maximum fiux density permissible with# I then increase-the flux density a out alsol attracting the silica particularly those grains containing some iron or having some hematite still adhering to the K.surface of the grain. By this mode of procedure I find I may recover substantially of the total iron of the ore and obtain thereby a concentrate averaging 52% Fe and the balance mainly silica which concentrate is readily adapted for use after sintering in the usual types of iron ore reduction furnaces and processes. As the iron ore itself is relatively of little value .unless and until concentrated and must'after concentration be able to compete from a cost standpoint with relatively Alow priced high grade ores, it is apparent that the device of the present invention is adapted to accomplish this very result. A relatively large tonnage per day may be treated with low labor costs as one man can supervise the operation of a large battery of such devices.

Having broadly and specifically described the present invention and several modifications of the same, it is apparent that the invention may be widely modified without departure therefrom and all such modifications are contemplated as may fall within the scope of the following claims.

What I claim is: y 1. Apparatus for the magnetic separation of dry materials, comprising in combination an inclined chute member tangent to a rearwardly extendingA arcuate portion, the degree of inclination of the chute being suiiicient to gravitationally feed the material to be treated in a relatively thin layer not over 3 particles .deep along vsaid chute .towards said arcuate portion, means to magnetically attract the magnetic particles of said material to the surface of said chute as the material approaches the said arcuate por. tion, means to'magnetically -move the attracted particles along the surface of vsaid chute and over the lip of said arcuate portion to a point on the underside of said arcuate portion adapted to provide a path of substantially free vertical fall for the said magnetic particles remote from the path of fall of the non-magnetic particles off the lip of said arcuate portion.

2. The apparatus of claim 1 wherein two said chutes are provided and are disposed opposite each other in a position to feed the said materials towards each other with the said arcuate portions located adjacent but in spaced relation and with a space gap therebetween, means to project an electromagnetic field of required intensity between said arcuate portions, said means includ- `ing electromagnetic poles provided with rotatable cylindricalshaped pole ends, having a diameter and length adapting the same to be located adjacent the under surface of' the said arcuate portion, the peripheral surfaces of said pole ends being provided with spaced and isof lated points or areas comprised of material of relatively high flux concentration as compared to the intervening areas, said spaced areas being discontinuous in the direction of rotation of said pole end surfaces. l

AUGUSTIN LEON JEAN QUmiEAU. 

